Objectives: The aim of this study was to identify the frequency and epidemiological characteristics of infections caused by multidrug-resistant microorganisms and to examine possible risk factors responsible for colonisation and infections with these pathogens. Study design: Cross-sectional study. Participants and methods: Study included 185 participants treated in the ICU of the Clinic for Anesthesiology, Resuscitation and Intensive Care during 2016 and 2017, who were colonised or had infection caused by multidrug-resistant hospital microorganisms. The participants' demographic and clinical data were taken from the medical records and microbiological protocol. Results: Before admission at the ICU 49.2% participants were colonised and 31.4% were infected by the resistant pathogen. The most common isolated pathogen was Acinetobacter baumannii. 60.5% participants were colonised at the ICU, 59.4% of them had infection prior to the admission at the ICU. Primary disease, surgical treatment and time spent in hospital ward favored colonisation and infection before admission at the ICU, while critical condition, artificial airway, mechanical ventilation, surgical intervention and time spent on ICU are considered risk factors responsible for colonisation and infection at the ICU. The difference in the incidence of infections between surgical and non-surgical patients was not found. Conclusion: ICUs are not the only reservoirs of resistant pathogens. One part of the patients is colonised or infected at the admission to the ICU, other part got infected or colonised at the ICU. Isolates are usually Gram-negative bacteria. The most common is Acinetobacter baumanii. Colonisation and infection at hospital wards and ICUs are contributed by the nature and severity of a disease, exposure to invasive therapeutic procedures and staying in surroundings with high prevalence of resistant microorganisms.